This application claims the priority of German Patent Application Serial No. 101 41 835.3, filed Aug. 27, 2001, the subject matter of which is incorporated herein by reference.
The invention relates to a device for locking at least two protective doors of an industrial machine, in particular the doors of an injection molding machine.
Many machines have protective doors to protect bystanders and operators of these machines. The protective doors should be allowed to open only when the process does no longer pose a risk. Otherwise, opening the protective doors when the machine is running will trigger an emergency stop. When all protective doors are closed, the state of the machine is switched to a ready state.
FIG. 1 shows a conventional device for locking a protective door 2. This device includes a momentary contact switch 4, a device for recognizing that the door(s) is/are closed, and an electromechanical lock 8. The momentary contact switch 4 is located on a door handle 10 of the protective door 2. The functionality of the momentary contact switch 4 can also be implemented using other devices. The functionality of the momentary contact switch can also be implemented at other locations of the industrial machine, for example in a machine control panel. The electromechanical lock 8, in particular the protective door lock, has an actuator 12 and a receiving device 14 adapted to engage with the actuator 12. In the illustrated embodiment, the actuator 12 can move in an axial direction as indicated by a double arrow 16. The actuator 12 is moved by an electric device 18. In the locked state, the actuator 12 is located inside the corresponding receiving device 14, which in the simplest case is a plate 20 with an opening 22. A sensor device 6, such as a protective door contact 6, is also closed in the locked state, indicating that the protective door 2 is indeed closed.
If the protective door 2 is to be opened, then the command xe2x80x9cMove machine/process into a safe statexe2x80x9d is triggered using the momentary contact switch 4 on the protective door 2. In response to the command xe2x80x9cMove machine/process into a safe statexe2x80x9d, the electric device 18 of the electromechanical door lock 8 receives a control signal to move the actuator 12 away from the receiving device 14 in an axial direction. After the receiving device 14 is released, the protective door 2 can be opened and withdraws from the protective contact 6. The xe2x80x9copenxe2x80x9d and xe2x80x9cclosexe2x80x9d motion of the protective door 2 is indicated by another double arrow 24.
If an industrial machine, for example an injection molding machine, includes several protective doors 2 and 26 (see FIGS. 2 and 3), then each protective door 2 and 26 is provided with a device of the type described with reference to FIG. 1 for locking the protective door 2 and/or 26. On an injection molding machine, the two protective doors 2 and 26 are referred to as xe2x80x9cmold closing doorxe2x80x9d and xe2x80x9cejector doorxe2x80x9d. It can be technically complex and expensive to protect an operator of such an injection molding machine.
It would therefore be desirable to provide a device than can simultaneously lock several protective doors of an industrial machine.
According to one aspect of the invention, at least two protective doors of an industrial machine, in particular an injection molding machine, can be locked simultaneously with a single locking device which includes a momentary contact switch, a device for recognizing a closed state of the protective door and a mechanical lock having an actuator with an associated receiving device, wherein one of the protective doors has at least one non-energizable actuator whose corresponding receiving device is associated with the second protective door.
This device advantageously eliminates for each additional protective door one electromechanical lock, one device for recognizing the locked state and one momentary contact switch. This design reduces the wiring cost and obviates the need for additional digital inputs and outputs of a machine controller. However, when using this particular device of the invention, the protective door that is equipped with the non-energizable actuator and the electromechanical lock, must be the last protective door closed, since this door is responsible for locking the other protective doors.
According to another aspect of the invention, a device for locking at least two protective doors of an industrial machine, in particular an injection molding machine, includes a momentary contact switch, a device for recognizing a closed state of the protective doors and a mechanical lock having an actuator with an associated receiving device. The actuator includes a transfer device with at least two additional actuators that engage with corresponding receiving devices that are each associated with a protective door.
With this arrangement, several protective doors can be locked simultaneously with a single electromechanical locking device. The transfer device transfers the locking motion of the actuator of the electromagnetic lock to additional spatially separated actuators. This locking device for locking several protective doors also reduces the number of additional components and the technical complexity. Unlike the first device, this device does not require that the protective doors are locked in a particular sequential order. The electromechanical locking device is only actuated after all protective doors are locked, locking all protective doors simultaneously, independent of their spatial arrangement.
Embodiments of the invention may include one or more of the following features. The energizable actuator and the at least one non-energizable actuator are implemented as a bolt, with the receiving device being in form of an opening. A sensor device can be disposed on at least one of the protective doors for recognizing a closed state of the at least two protective doors. The sensor device, which can be a protective contact, and the mechanical lock can be arranged on opposite sides of a protective door.
The transfer device can include a plate, for example a plate having a triangular shape, in with case the at least two additional actuators can be arranged on the side of the plate that faces away from the energizable actuator.
The device can advantageously be used with an injection molding machine that has as one of the protective doors a closing door and as another one of the protective doors a discharge door.
Further features and advantages of the present invention will be apparent from the following description of preferred embodiments and from the claims.